In Japanese Patent Application Publication No. 2006-200466 (JP-A-2006-200466), an output control apparatus for an internal combustion engine is described. In this apparatus, the desired throttle valve opening degree is calculated using an inverse model of the intake system model and an inverse model of the throttle model in order to achieve a desired torque of the internal combustion engine with good response. In the above-described apparatus, the engine speed and the valve timing, which are parameters to be inputted into the inverse model, are processed with a filter to stabilize the control of output from the internal combustion engine.
When a differentiation is included in the process of deriving the model expressions as in the case of the related art described in JP-A-2006-200466, the system becomes overly responsive to the engine speed and the pressure in the intake pipe that continuously vary by a small amount. More specifically, when the parameters in the model expressions include a parameter having high-frequency oscillatory components, such as the engine speed, unexpected noise is amplified when the parameter is differentiated.
It is conceivable to use a filtering process as in the case of the related art described in JP-A-2006-200466 in order to solve the above problem. However, although such a filtering process contributes to improvement in stability of the control, there is room for improvement in the response of the system.